Sources said there were fears Abedi may have taken advantage of the conflict to make the simple journey across the Med to Syria without alerting the British authorities.

One revealed: “His potential ties to Syria now very much forms one line of inquiry.”

Cops are also probing whether Abedi, who is believed to have been known to MI5, acted alone or as part of a larger extremist network to carry out the worst terror attack Britain has seen since the 7/7 London bombings.

And Met Police Assistant Commissioner Mark Rowley admitted there were “gaps in our knowledge” about Abedi and the PM said it was possible a “wider group of individuals” could have been involved in the “cowardly” attack.

Eight-year-old schoolgirl Saffie Roussos was named as one of the victims along with student Georgina Callander, 26-year-old John Atkinson and brave aunt Kelly Brewster, 32, who shielded her niece from the deadly blast.

Mums Alison Howe, 44, and Lisa Lees, 43, were also killed while waiting for their kids to leave the show and teenager Olivia Campbell who sparked an emotional TV appeal have also been listed among the dead.

The latest victims confirmed dead are Angelika and Marcin Klis, a Polish couple whose daughter launched a desperate appeal to find them yesterday.

Cops swooped on two addresses in Manchester after the deadly nail bomb blast

US security sources, citing British intelligence officials, said Abedi was born in 1994 to parents who had fled to the UK to escape the Gaddafi regime.

His dad is understood to have left the UK in 2011 to try and overthrow the Libyan leader.

The Mail Online reports when Gaddafi was killed the family put a massive flag on the roof of their house.

Neighbour Debbie Smith, 53, said: “I think they were glad he was dead.”

Home Secretary Amber Rudd has said Abedi was known "up to a point" to the intelligence services.

When asked in an interview with the BBC this morning if the attacker was a "lone wolf" or not Rudd said: "It seems likely, possible, that he wasn’t doing this on his own."They are believed to have emigrated to London before moving to south Manchester.

Abedi’s family have told of their horror at finding out he was behind the massacre.

They described the fanatic as a “brilliant” footballer who loved Manchester United and Spanish giants Real Madrid.

One male relative, who asked not to be named, told The Sun how he had seen Abedi just ten days ago looking “happy, relaxed and smiling” as he secretly plotted the attack.

Thousands paid their respects to the victims at a vigil in Albert Square outside Manchester Town Hall

Dr Sam Grogan, the university's Pro-Vice Chancellor Student Experience, said: "All at the University of Salford are shocked and saddened by the events of last night. Our thoughts are with all those involved, their families and their friends.

"We have provided, and continue to provide, support to all students and staff who have been affected."

Abedi and his brother reportedly worshipped at Didsbury mosque, south Manchester, where their father was a "well-known figure".

Mosque trustee Fawaz Haffar said Abedi's dad used to perform the azan, the call for prayer before 1,000 of the faithful and his brother worked as a volunteer.

When asked whether he had ever seen the terrorist praying at the mosque, he said: "He probably did, I have never seen him, I don't know him.

"I came earlier to ask any of the employees whether they knew him, people said they don't know him. There are many mosques, he may be attending another mosque. I honestly do not know."

Salman reportedly stopped going to the mosque in 2015 as he objected to anti Isis comments, according to Mohammed Saeed, the imam of Didsbury Mosque.

He said: “Salman used to come to the mosque occasionally, he wasn’t particularly friendly towards me because he didn’t like my anti-IS sermons.

“He didn’t like what I was saying and showed me the face of hate. He came to the mosque less and less after that.”

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Following an emergency Cobra meeting, Mrs May said the independent body which sets the threat level has increased it from “severe” to “critical”.

She said: "This means that their assessment is not only that an attack remains highly likely but that a further attack may be imminent.

The defiant PM described the massacre as “callous and cowardly” and declared “terrorists will never win”.

“His victims were innocent children, young people and their families - our thoughts and prayers are with them all.

"I want to re-iterate what I said about the professionalism of the emergency services and the bravery of the people in Manchester.

"Through their actions, they proved that cowardice will always be defeated by bravery, that evil can be overcome by good and that our values, the liberal, pluralistic values of Britain, will always prevail over the hateful ideology of the terrorists.

ISIS said in a statement published by its Amaq News Agency (a news outlet linked to ISIS in Syria) : “With Allah's grace and support, a soldier of the Khilafah managed to place explosive devices in the midst of the gatherings of the crusaders in the British City of Manchester.

"This was in revenge of Allah’s religion, in an endeavour to terrorise the mushrikin, and in response to their transgressions against the lands of the Muslims.

Fans flee from seats in the Manchester Arena as panic spreads after explosion

“We just grabbed each other and got away. One lass was laying in her mother’s arms. I’m not sure if she has collapsed in shock or was injured.”

Abby Mullen said she was also leaving the venue at the time of the blast and refuted earlier claims it had been caused by a speaker or balloon, which had circulated on social media after the explosion.

She wrote on Facebook: "As we where leaving a bomb or explosion went off centimetres in front of me.

"Peoples skin/blood&faeces where everywhere including in my hair & on my bag. I'm still finding bits of god knows what in my hair. I am fine & back in my hotel I hope everyone involved and in front of me is okay."

Chris Parker, 33, was walking through the station towards the box office when the explosion went off.

He said he saw at least six ­people seriously injured on the floor and told The Sun: “I was walking through and one huge bang went off.

“There was nuts and bolts flying everywhere, and also human flesh. It was just one bang and a white flash. I treated a woman called Pauline. I’ve got blood on my hands. It was like a war zone inside where the box office is.

“There looked to be at least six people potentially fatally wounded. I saw one woman’s leg off. It is mayhem.”